Issue 33 - The chill factor

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The chill factor

Ironically few subjects are likely to make a whisky aficionado's blood boil quicker than that of chill filtering. Ian Wisniewski presents the arguments

It's all very well for the militant malt brigade to criticise the industry for chill filtering, but as consumers we also have to take our share of collective responsibility. Okay, not all of us are squeamish, but many consumers would be put off if their dram looked different after adding water or ice.

Moreover, the damaging effect this could have on consumer confidence, and perception of whisky as a quality product, not to mention apparently ‘defective' bottles being returned, provides a valid (if not compulsory) reason for chill filtering. Without chill filtering, whisky bottled below 46% abv throws a cloudy haze either when diluted with water, or when subjected to lower temperatures, such as adding ice.

Similarly, whisky stored at a low temperature can result in unappealing precipitation in the bottle (which vanishes once the temperature rises again). The principal culprits causing cloudiness are long chain fatty acids and their esters. Reducing alcoholic strength, or temperature, changes the whisky's solubility (ie. the ability to hold the fatty acids in solution) and they begin to precipitate out.

Consequently, chill filtering ‘protects' us from this reality, and has been applied to the vast majority of malts and blends since the 1960s. Fatty acids are derived from cereals and yeast cell wall material during fermentation (some of which carries over into the new make spirit). Comprising the largest molecules in whisky, fatty acids are also present in significant am...